LONDON (Reuters) - World Chess Championship officials might rethink the role of ceremonial starter after Hollywood actor Woody Harrelson knocked over a king and moved the wrong pawn in a comical start to the 2018 event in London on Friday.

Norwegian title holder Magnus Carlsen and Fabiano Caruana were bemused onlookers as the U.S. actor began their eagerly anticipated match-up by knocking over the American challenger’s king, the move that traditionally signals a concession.

Caruana had asked the “Hunger Games” and “Cheers” actor to move his pawn to start the game, only for Harrelson to hit the king and moved a different piece.

A bewildered Caruana initially appeared to accept the mistake before officials allowed the pawn to be returned. A grinning Harrelson then moved the correct pawn before quickly exiting the stage.

It was a memorable start to the 1 million euro (£873,350) contest, which organisers expect to be watched by millions around the world. The duo are scheduled to play 12 matches through November, with the winner the first to reach 6.5 points.

Carlsen, 27, has won the last three championships and is the world’s top ranked player. He became a chess grandmaster at 13.

Caruana, 26, is bidding to become the first American to win the title since the enigmatic and volatile Bobby Fischer beat Russia’s Boris Spassky at the height of the Cold War in 1972.

Reporting by Will Russell; Writing by Patrick Johnston; Editing by Kevin Liffey